Name one example of a 2026 car with the same size, fuel type and class where the difference in mileage is >=50%

I have a very hard time believing this, especially with fuel economy and emission regulations

The 2026 Toyota Corolla GR has 22mpg combined, and the normal 2026 Corolla has 35mpg with gas or 50mpg with a hybrid powertrain.

It is true that fuel economy regulations make it much less practical to deliver gas guzzlers out of pure laziness. (As you may know, the Corolla GR is by far the most expensive of these options, because it's designed to achieve horsepower over mileage.)